We saw the plane too - it was very worrying. My son said that he heard at school that it was a Russian Cargo plane and that it definitely landed at the unused/emergency runway at the nearby Yeovilton airbase. Several people saw it circle Yeovilton before it came in to land. Very strange indeed.

Thanks for the reply!

It did cross my mind actually that it may have been heading for Yeovilton. However its manoeuvres in the sky still looked a bit risky.

I also couldn't help wondering where it had flown from and if it was a cargo plane (which are the same size as a passenger jet) why it had not landed at Exeter, Bristol or Bournemouth as it would have flown over one of these airports to get to Yeovilton.